Answer:
x^2 + 5x - 84 = 0
x = 7
Step-by-step explanation:
let the sister's age = y
sister's age (y) = 5 + x equation 1
xy = 84 equation 2
Make y the subject of the formula in equation 2
y = 84/x
equate equation 1 and 2
84/x = 5 + x equation 3
Multiply equation 3 by x
84 = 5x + x^2
x^2 + 5x - 84 = 0
tjis can be solved using quadratic equation
x^2 -7x + 12x -84 = 0
x(x + 12) -7(x + 12)
x = 7 or - 12
age cant be negative so his age is 7
Answer:
x=7−√10 or x=7+√10
Step-by-step explanation:
−5(x−7)2+30=−20
Step 1: Simplify both sides of the equation.
−5x2+70x−215=−20
Step 2: Subtract -20 from both sides.
−5x2+70x−215−(−20)=−20−(−20)
−5x2+70x−195=0
For this equation: a=-5, b=70, c=-195
−5x2+70x+−195=0
Step 3: Use quadratic formula with a=-5, b=70, c=-195.
x=
−b±√b2−4ac
2a
x=
−(70)±√(70)2−4(−5)(−195)
2(−5)
x=
−70±√1000
−10
x=7−√10 or x=7+√10
Distance= the square root of (x2-x1)^2 +(y2-y1)^2 so (-3-(-3))^2 + (23-(-11))^2= 0^2+34^2=
0+1156= 1156 and the square root of that is 34 so your final answer is 34
For roots r1 and r2, the factors are (x-r1)(x-r2)
given
r1 and r2 arer 5+i√2 and 5-i√2
(x-(5+i√2))(x-(5-i√2))=
(x-5-i√2)(x-5+i√2)=
remember that i²=-1
x²-10x+27
When he was 14 his dad was 42
now the child is twice 14... = 28...
